Zheng, W., Y. Li, Q. Gong, H. Zhang, Z. Zhao, Z. Zheng, B. Zhai, and Z. Wang. “Improving Yield and Water Use Efficiency of Apple Trees through Intercrop-Mulch of Crown Vetch (Coronilla Varia L.) Combined With Different Fertilizer Treatments in the Loess Plateau”. Spanish Journal of Agricultural Research, Vol. 14, no. 4, Dec. 2016, p. e1207, doi:10.5424/sjar/2016144-9575.